Repeated dose toxicity study of Vibrio cholerae-loaded gastro-resistant microparticles.

CONTEXT: Microencapsulation of antigens has been extensively studied over the last decades aiming at improving the immunogenicity of vaccine candidates. OBJECTIVE: Addressing microparticles (MPs) toxicity in rats. MATERIAL AND METHODS: Spray-dried Eudragit® L 30 D-55 MPs and Eudragit® L 30 D-55 alginate MPs were elaborated and characterized. MPs obtained were administered to rats, three groups were defined: G1, control group; G2, administered with Vibrio cholerae (VC)-loaded MPs; G3, receiving VC-loaded alginate MPs. Animals received three vaccine doses. Body weight, food and water intake were controlled during the study. Haematological parameters, vibriocidal titres, organ weight and histology in necropsy were also analyzed. RESULTS: All animals grew healthy. Body weight gain, food and water intake and haematological parameters remained within physiological values, showing no treatment-related differences. Moreover, organ weight changes were not detected and animals developed protective vibriocidal titres. CONCLUSION: VC-loaded MPs and VC-loaded alginate MPs have proved to be safe and effective in the assessed conditions.

Histopathological Study of the Lungs of Mice Receiving Human Secretory IgA and Challenged with Mycobacterium tuberculosis.

BACKGROUND: Humoral and cellular immune responses are associated with protection against extracellular and intracellular pathogens, respectively. In the present study, we evaluated the effect of receiving human secretory immunoglobulin A (hsIgA) on the histopathology of the lungs of mice challenged with virulent Mycobacterium tuberculosis. METHODS: The hsIgA was purified from human colostrum and administered to Balb/c mice by the intranasal route prior to infection with M. tuberculosis or in a pre-incubated formulation with mycobacteria, with the principal aim to study its effect on qualitative pulmonary histopathology. RESULTS: The intranasal administration of hsIgA and the pre-incubation of mycobacteria with this preparation was associated with the presence of organised granulomas with signs of immune activation and histological features related to efficient disease control. This effect was highly evident during the late stage of infection (60 days), as demonstrated by numerous organised granulomas with numerous activated macrophages in the lungs of treated mice. CONCLUSION: The administration of hsIgA to mice before intratracheal infection with M. tuberculosis or the pre-incubation of the bacteria with the antibody formulation induced the formation of well-organised granulomas and inflammatory lesions in lungs compared with non-treated animals which correlates with the protective effect already demonstrated by these antibody formulations.

Pharmacology and toxicology of an oral tablet whole cells inactivated cholera vaccine in Sprague Dawley rats.

Here we further investigate the pharmacological and toxicological properties of a cholera vaccine based on inactivated whole cells presented in either enteric coated (COA) or uncoated (U/C) tablet formulation from Vibrio cholerae C7258 strain. Tablets were dispersed in 2mL drinking water and administered orally to Sprague Dawley rats distributed in five groups (I COA7, II U/C7 immunized at 0, 7, 69days and III COA14, IV U/C14 immunized at 0, 14, 69days and V control group). Serum vibriocidal antibody response was measured after the administration of two doses with an interval of 7-14days. To further investigate the toxicological aspects a third dose was applied 10 weeks after the initial one. Animals were observed daily and water and food consumption was measured every other day. Periodic blood extractions were performed for hematology, biochemistry, and the titer of serum vibriocidal antibodies was determined. Anatomopathological analysis was performed at days 3 or 14 after the third dose. Results from clinical observations, as well as from water and food consumption and body weigh indicated no toxicity of the vaccine product. Meanwhile, no biological differences were found among different groups in hematological, hemo-chemistry, and anatomopathological studies. Moreover, enteric coated and uncoated tablets against human cholera were found to induce an immune response in rats.

Toxicidad aguda oral e irritabilidad de la mucosa oral con una formulación de tabletas de Tamarindus indica L / Acute oral toxicity and irritability of the oral mucosa with a tablet formulation of Tamarindus indica L

In this study, the possible preclinical toxic effects of the Tamarindus indica L tablets were evaluated by the acute oral toxicity (AOT) and oral mucosa irritation (OMI), adapting guideline OECD 423 and ISO 10993-10, respectively. The AOT was evaluated, using the Class Toxocity Method in Sprague Dawley females rats and the OMI was assessed in sirian hamsters, according to the acute exposure method. Any sign of toxicity were not observed in the study. No animal death was occurring and the body weight increase in the two experimental groups was not statistically different. Slight irritation of the oral mucosa of the animals was observed, but this fact didn't impede them to feed appropriately and they body weight increase normally during the assay. Tamarind tablets were framed as non toxic substance and they produce a “light irritability” of the oral mucosa.

En este trabajo se evaluó a nivel preclínico, los posibles efectos tóxicos de las tabletas de Tamarindus indica L. Se ensayó la toxicidad aguda oral, por el método de las clases de toxicidad, en ratas hembras de la línea Sprague Dawley y la irritabilidad de la mucosa oral en Hamster sirio, según las normas OECD 423 y ISO 10993-10, respectivamente. Durante el estudio de toxicidad aguda, no se observaron signos de toxicidad, ni muerte. El peso corporal en ambos grupos experimentales aumentó y no fue diferente estadísticamente. En el estudio de irritabilidad, se observó una ligera irritación en la mucosa de los biomodelos. Esto no les impidió alimentarse adecuadamente y se observó un incremento del peso corporal de ambos grupos experimentales. Se determinó que las tabletas producen una irritabilidad “leve” de la mucosa oral y no clasifican como tóxicas según las normas internacionales de referencia.